           |
|
-
- Hybrid Mulching
- Plastic with natural mulch saves time, extends plastic to three seasons
- By Karen Gentry
Associate Editor
- New York grower Lou Lego has discovered a way to reap the benefits of plastic mulch without all of the problems by using what he calls a “hybrid mulch approach.”
It all started several years ago after he planted rye in the fall that grew very tall and made a “beautiful mulch.” Lego, of Elderberry Pond Country Foods in Auburn, N.Y. was having trouble with the plastic he was using to suppress weeds in his vegetable plantings.
The new approach evolved through his experiences in planting and cutting cover crops. The tall cover crops become a living mulch while protecting the plastic from sunlight and gullies of water that tend to form after wet weather. Plastic mulch would often wash out between the rows where weeds would grow that were very hard to remove.
“We started doing it about three years ago,” said Lego. Hybrid mulching saved him from 1999’s wet weather. Last summer he was awarded a grant from the Sustainable Agriculture Research and Education (SARE) program to demonstrate hybrid mulching, record it and report on it.
“I’ve never seen it before. I think it’s a new technique. I think it would be best for large field growers of pumpkins, squash and also tomatoes,” said Lego. “It works very well. Now we’re doing it on 30% of our farm. Overall I think it’s an extraordinary system for growing vegetables,” he said. By using the plastic for over three years, Lego saves labor and plastic costs.
Most warm weather crops grown in upstate New York perform better on plastic mulch, according to Lego. This includes melons, cucumbers, squash, tomatoes and peppers. When the plastic mulch is in place early in the spring the soil under the mulch warms quickly and remains moist well into the summer.
Lego outlined some of the drawbacks of plastic mulch. Mulch laying is time consuming and expensive. The mulch generally lasts only one season and removal of the muddy remains is no fun. The plastic then needs to be carted to a landfill for disposal. Weeds between the rows, particularly on the edges of the plastic mulch used on a sloped field can result in severe water erosion between the rows and often in removal of the soil anchoring the plastic. Another problem is that fruit resting on the plastic during the warm summer months can become discolored or rotted.
The hybrid mulch approach where both living mulch and plastic mulch are used produces better crops and, most importantly, it provides protection for the plastic mulch extending its life for several years, according to Lego.
In field trials last summer, hybrid mulching was compared to mulching with a killed cover crop. Lego also compared two approaches to hybrid mulching, spring field preparation and fall field preparation. Melons, summer squash, and tomatoes were grown in the trial.
Field preparation
In both the fall and spring approaches, field preparation is very important, Lego said. The field should have been cover cropped or otherwise improved to have good quality soil with high organic matter and nutrient levels. This is necessary because the field will not be tilled or cultivated for at least two years from the time of planting. The field should be tilled, dragged and free of large rocks that could tear the plastic.
Seeding and mulch laying
In the fall preparation approach, the field is seeded with rye grain. This can be done anytime between late September and late October, but earlier is better if the soil moisture is high enough to germinate the grain. Lego seeded the field using an old Ontario grain drill and at the highest rate the drill will support, which is about 150 pounds per acre. After seeding the grain the mulch was put down. In the areas where the plastic covers the grain the grain either fails to germinate or germinates and is smothered by the plastic.
In these trials a 48-inch, 1.5 mill thickness of Polyon film was used. Over the years Lego has found this to be the most durable field mulch. The mulch was placed in rows of nine feet center-to-center spacing. This left about six feet of soil between the rows including the soil covering the plastic edges. The spacing was wide because of the planned multi year crop rotations on the plastic, which was to include melons and squash.
Fall and early spring growth
During the late summer and fall the grain grows to several inches tall, holding the plastic and preventing erosion from fall and early spring rains. In early spring the grain greens up early and grows rapidly. By the time the sun is high in the sky, the grain has grown to a foot or so and begins to protect the plastic from ultra-violet rays, which are the primary source of plastic mulch degradation. By this time the soil under the mulch has warmed, and in mid to late May the tomatoes are transplanted. The environment provided by the tall grain on each side of the plastic rows is perfect for transplants, according to Lego. They are protected from the drying wind, warmed by the plastic mulch, and grow very vigorously.
Cutting the mulch
In mid June or early July the mulch between the rows is over two feet high and beginning to form seed. At this point the grain mulch is cut. Lego said the grain was cut using a walk behind sickle bar mower and the grain near the edges of the plastic fell over the plastic. This is important to provide added protection of the plastic from the sun over the hot summer months. This also was beneficial in keeping the soil under the plastic from getting too warm during July and August. Another benefit is that the fruit is held off the plastic by the cut grain protecting it from discoloration that sometimes occurs when tomatoes or melons lie directly on the hot plastic. Following cutting, the red plastic is so thoroughly covered by the mulch that is it not evident that there is plastic mulch in the field. No further work is required to the field during the harvest season, and in the summer 2000 trial, weed emergence between the rows was minimal in a particularly wet and otherwise weedy year, according to Lego.
Post harvest preparation
One of the primary objectives of the hybrid mulch approach is to reuse the plastic for at least two and hopefully three years, according to Lego. For this reason it is important to clean the plant residue from the field in fall or early spring. Fall is better in decreasing disease carryover, but for continued plastic protection and ease of cleanup, early spring is better. When cleanup is performed in the fall, winter rye grain may be re-seeded. For this, use a spinning type seed spreader and seed right over the plastic and into the soil between the rows. Prior to seeding Lego roughs up the soil lightly with a small walk behind the cultivator. By November there is a good stand of six to eight inch tall rye between the rows for the over-wintering. With spring cleanup, he seeds oats between the rows and gets a fair stand prior to transplant placement in late May.
Crop rotations
When using the plastic for several years, it is recommended (though not demonstrated) that it is best to plant vegetables from different vegetable families in successive years. Lego starts with solanaceae (tomatoes) the first year, then plant cucurbits the second (melons, cucumbers, squash or pumpkins), and then in the final year crucifers (cabbage, broccoli, Brussels sprouts or collards). All of these crops benefit from planting on plastic. They selected this rotation order because, in their experience, it progresses from the most difficult to the easiest crops for disease control. He cuts off the plants from the previous year to minimize damage to the plastic that might result if the plants are pulled out. Each year the new holes placed in the plastic can be fertilized specifically for that crop at planting if required. Lego says they have been through the entire three-year cycle with no significant disease control or plant nutrition problems.
Some final notes
Only the fall preparation method is mentioned above. In the spring field preparation method the field is prepared in the same way as described, but in mid to late April. The grain Lego used is oats. Lego said he has not had much success with the spring preparation approach due to the unpredictability of the spring weather. Heavy rains and late frosts can slow grain He intends to try other spring planted covers such as red clover and rye grass, particularly for the third season rotation where complete coverage of the plastic may not be necessary.
“We have found the hybrid mulch approach to be an efficient, low input way to manage vegetable crops in upstate New York. In our trials, transplants and seeds got a two to three week head start over plants or seeds placed in killed grain mulch,” Lego said. He said in dry years the plastic mulch retains moisture, and in overly wet years it moderates the moisture. The living mulch growing in the wide spaced rows protects and improves the soil over the three-year rotation cycle. It is almost like having the field in continuous cover crop for the three-year crop rotation.
Elderberry Pond Country Foods is a certified organic farm with a store on the property. Lego’s operation includes 100 acres with 30 acres of fruits and vegetables. He operates a Community Supported Agriculture (CSA) program with 50 families receiving a bushel of produce each week. They also sell to farmers markets. He grows 70-80 different vegetables, pears and 100 varieties of apples. Most crops are grown in small quantities although he has a few acres of potatoes and sweet corn.
Lego says CSA’s are becoming increasingly popular in his region. “I think it’s the most profitable way to do vegetables. It fits better to the farmer’s schedule,” said Lego.
For more information about hybrid mulching, contact Lego at (315) 252-3977.
|
|
